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| Titel |
Soil moisture controls on patterns of grass green-up in Inner Mongolia: an index based approach |
| VerfasserIn |
H. Liu, F. Tian, H. C. Hu, H. P. Hu, M. Sivapalan  |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 2 ; Nr. 17, no. 2 (2013-02-26), S.805-815 |
| Datensatznummer |
250018804
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| Publikation (Nr.) |
 copernicus.org/hess-17-805-2013.pdf |
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| Zusammenfassung |
| Water availability is one of the most important environmental controls on
vegetation phenology, especially in semi-arid regions. It is often
represented in terms of soil moisture in small-scale studies, whereas it
tends to be represented by precipitation in large-scale (e.g., regional)
studies. Clearly, soil moisture is the more appropriate indicator for root
water uptake and vegetation growth/phenology. Its potential advantage and
applicability needs to be demonstrated at regional scales. The paper
presents a data-based regional study of the effectiveness of novel water and
temperature-based indices to predict spring vegetation green-up dates based
on the Normalized Difference Vegetation Index (NDVI) observations in the
grasslands of Inner Mongolia, China. The macro-scale hydrological model,
VIC (Variable Infiltration Capacity), is employed to generate a soil moisture database across the region. In
addition to a standard index based on temperature, two potential hydrology-based indices for prediction of spring onset dates are defined, based on the
simulated soil moisture data as well as on observed precipitation data.
Results indicate that the correspondence between the NDVI-derived green-up
onset date and the soil-moisture-derived potential onset date exhibits a
significantly better correlation as a function of increasing aridity
compared to that based on precipitation. In this way the soil-moisture-based
index is demonstrated to be superior to the precipitation-based index in
terms of capturing grassland spring phenology. The results also showed that
both of the hydrological (water-based) indices were superior to the thermal
(temperature-based) index in determining the patterns of grass green-up in
the Inner Mongolia region, indicating water availability to be the dominant
control on average. The understanding about the relative controls on
grassland phenology and the effectiveness of alternative indices to capture
these controls are important for future studies of vegetation phenology
change under climate change. |
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